I personally would prefer a combination of 40xx. Should not take more than 3 ICs, and will work more reliably than the microcontroller, probably take less power and have wider voltage range in operating.

So he's added one extra complexity and decided it is worth of requiring a 16MHz microcontroller rather than simply adding another transistor to do the job? It's like saying I need to walk to the train station but it's only slightly too far to walk. I know I'll buy a Ferrari for this commute.

What an epic waste of a microcontroller. He and you should turn in your geek card if you haven't figured out how to make this all USB controlled and coded up a computer interface within the afternoon.

Well an Arduino would not be the right choice if you were building a large run of a commercial product. But we're talking about DIY here. The advantage of using something more powerful and general purpose like an Arduino is:
1. Easier to rapidly prototype, tweak your setup, or add features. (It's faster to re-code your Arduino than to rewire some electronics you soldered.) You can increase the scope/complexity of your project quite easily.
2. If you're already familiar with the Arduino, and have one on-hand

Are you suggesting that one should use discrete components, or that any microcontroller would do? Since all the cool kids are using them, it means the dev tools are decent and tutorials and examples are plentiful, thus it's a good idea to use one. See x86, Windows, PC architecture for examples. At least they didn't plaster Arduino into the headline.

I agree that the Arduino is overkill for a basic sound trigger - but projects like the Camera Axe [cameraaxe.com] make a lot more sense. I use a variation on the Camera Axe for photographs of lightning among other things.

I did this in the 1970's for a photography project using an SCR to handle the high strobe trigger voltage (used to be ~160 volts on the shutter contacts) and the amplifier from a portable tape recorder to amplify a microphone to enough voltage to trip the SCR. With a strobe mounted off the camera and the camera on bulb setting, I took pictures of light bulbs crashing onto the sidewalk. Due to the lighting angle, most people thought it was taken in the daytime in sunlight. I adjusted the delay after impact by changing the distance of the mic from the bulb. 6 feet provides a good delay. With the mic too close, the bulb looks like it is sitting on the sidewalk with a few cracks in the glass. The delay was necessary to get the bulb in a reasonable amount of shards.

I did this in 2004 for a photography project using 4 transistors a few resistors, microphone and battery. These days flash triggers are low voltage. The SCRs were necessary back then, but seriously what is it with people throwing a 16MHz microcontroller and code to run it at something that can be made with a tiny handful of discrete components.

But you should hop on there and show us how to make one without the expensive Arduino! Lots of us out there can follow instructions, and learn a little in the process, but wouldn't know how to make our own from scratch.:)

Because otherwise there wouldn't be anyone to complain about it on Slashdot? Do you read your email in pine over a serial terminal too?

The photographer had minimal electronics experience and simply used what knowledge and equipment he already had on-hand to create a useful hack. The great thing about Arduino is that it's flexible and simple. It allows people to slap together all manner of interesting projects without the benefit of an electronics engineering degree. In fact, it was explicitly designed as a

Somewhere in a box here I have a copy of Hobby Electronics from the early 1980s, which has a sound-triggered flash sync unit. If I recall correctly, it used a couple of opamps as a mike amplifier/filter and a comparator, and an SCR to actually trigger the flash.

It's a shame there aren't any pictures, or any description of how it actually works. It would have been nice to see his results.

Hell, somewhere in a box here I've got a reprint of an old Gernsback magazine from the 50's which has a sound-triggered flash unit with delay. It uses a single valve as a class C amp (to give an adjustable threshold & immunity from background noise), a longish-timebase switchable R-C filter as an adjustable delay, and another single valve output stage to drive (IIRC) a B-C flash.

Also, didn't Doc Egerton publish the schematics of his strobes (not the same thing, admittedly, but close) back in the 30's?

I'll take a stab at it: Because it allows a software developer to do things that previously required a hardware developer (EE), for certain problems. This unbinds prototyping from a certain educational requirement, opening the field to more participants. For one-off projects of value, the cost of an Arduino board may be low enough to be considered negligible.

Also, the thing about this type of high speed photography is that you're triggering the light source... so if you're trying to photograph something that creates its own light, these strobe-triggering devices are going to do you no good at all.

To do that, you'd need to trigger a high speed shutter, which is a lot harder to do.. there's usually a lag between when a shutter is triggered and when it actually takes a picture, and the mechanical shutters on most SLR's don't actually go much faster than 1/250s.

An LCD cover over your lens may be perfect. The power triggered by an LDR or light dependent diode via a comparator. Maybe a capacitor and a potmeter somewhere to set the shutter time. Set the trigger up so it is default ON.
The LCD cover could theoretically be taken from some 3d shutter glasses (preferably glasses which have been mauled by a dog/crushed by a behind, but with one glass intact)

Real life, macroscopic events (i.e. stuff you'd want to photograph) happen at speeds that are closer to the speed of sound rather than that of light, so catching the very first wave of photons probably would not be very useful practically, not to mention insanely more difficult.

Even better... Just open your camera's shutter and put your hand in front of the lens until you see a lightning strike beginning. Remove your hand for just the amount of time that you see lightning. Then, put your hand back without closing the shutter. Repeat for however long you want to leave the shutter open, say 30 seconds. If you capture a few lightning bolts this way, you end up with a shot that looks like Zeus was VERY angry.

You don't need a flash for fireworks either. So why am I surrounded by people taking flash pictures of the sky whenever I go to a fireworks show? So far I have been able to resist grabbing them by their collars and screaming at them, but I'm not sure how long I can hold out.

Taking photos of lightening at night is very doable using this method. But not when you are trying to take some of the most beautiful lighting pictures... which occur during the day. Using your reflexes to time shutter open/close is more luck than skill.
Even at night, depending on the dSLR camera, the amount of time it takes for the camera to process a bulb setting and store the image can introduce long delays between shots, and missed opportunities. Bulb settings increase the noise in a shot the longe

Using a sound trigger to capture lightning strikes is counterproductive.
Using an IR sensor to measure the ambient IR, then trip the shutter when the IR spikes up works a treat, though. I built a variation on the Camera Axe [cameraaxe.com] last summer, and have been using it to take daylight photos of lightning strikes like this one [flickr.com].

I just used a cable release and a camera in "bulb" mode. Point the camera in the general direction of the storm, hold the shutter open for 15 seconds or until you get a good lightning strike, repeat. For daytime work, add a neutral density filter and reduce the exposure time.

6ms is long enough for something (like a balloon starting to pop) to happen.

Most people, if they try hard enough, can count to 10 aloud in 1 second. That means they are speaking with the capable thought around 100ms. Now, just imagine how high you can count in your mind, not speaking aloud, in 1 second. How many instant thoughts can you get? How many milliseconds is it to process the next number in your counting scheme for you?

Now try watching a baloon pop. Try capturing that moment where the shape is Juuuu

Seeing how light travels much faster than sound, my initial reaction is that this is a terrible idea.

Didn't bother viewing the linked video, eh?

The idea works pretty well because things with mass tend to move slowly, so despite the latencies involved and differential speed of sound and light, the described mixed digital / analog device works quite well to capture a mid-pop baloon or breaking wine glass. But then there are all of those classic Doc Edgerton photos that were taken with just analog circuitry, and they worked fine, too. Indeed, Prof. Edgerton made quite a career for himself at MIT using just

For pretty much anything happening high-speed, you want to take your photo slightly after whatever triggering event happens. If you're firing a gun, you want to see the bullet exiting the chamber, not the initial loud explosion when the hammer hits the bullet inside the gun. With a glass shattering, you want to see shards and fragments suspended in mid-air with a hammer partially through the glass, not the initial impact of the hammer before the glass has broken up.

A large portion of the canon cameras support CHDK (canon hack devkit). One of the nice features included in this is motion detection. This requires no external components to get it working, as it uses the CCD for triggering. There are numerous scripts that use CHDK to implement delays, time laps photo sequences or other funky actions. Most of the supported cameras are fast enough to capture lightning.

Back then, a similar project used op amps to trigger a flash unit. It was an article in one of the electronics mags I saw back in the late 1970's, titled "Build the Thunderbolt". (I Googled it, but came up empty.)

You adjusted the timing of when the flash was triggered, by moving the microphone closer or farther from the sound source. You could also have added a 555 timer, if you needed a longer delay than was feasible with a longer distance.

It reminds me of a discussion at the Electronics firm I am consulting for. They needed to add a 1/2 second delay to the startup of a device in a new product. I suggested they add a 555 timer circuit. They looked at me like I had two heads. Their solution was to throw a microcontroller into the product. Come on, guys! It can be done with a 555, a cap, and two resistors. It's crash-proof, too. Whatever happened to K.I.S.S?

Of course, it all depends, and I've not seen your design, so it could be that a 555 is simpler. In other cases, a microcontroller may be simpler. What's cheaper also depends on the circumstances. Price at digi-key for a NE555 from TI is 29 cents, while their cheapest microcontroller (PIC10F200) is only 34 cents (both @ 100 pieces). The microcontroller also comes in SOT23-6, so it takes up less board space, not even including the C and Rs. And maybe the microcontroller, in the same circuit, can also replace

I suggested they add a 555 timer circuit. They looked at me like I had two heads. Their solution was to throw a microcontroller into the product. Come on, guys! It can be done with a 555, a cap, and two resistors. It's crash-proof, too. Whatever happened to K.I.S.S?

A PIC like the 12F675 has eight pins, like the 555, and needs no external components at all. What can be simpler than that?

After I got a 100-pack of 12F675s at a special discount price I decided never to use a 555 again.

Multiply it by thousands and those capacitors and resistors begin to add up, multiply it by millions and the printed circuit real estate plus solder needed for the passive components start having a price impact. Flashing and testing a PIC takes less time than inserting, clipping leads, and soldering a couple of components.

Anyhow, when was the last time you needed just a half-second delay and nothing else from a circuit? With a PIC, the connections are the limit. From six pins in an 8-pin DIP to 40+ or more

The units being made are all surface-mount. No insertion or drilling or clipping. There are already dozens of parts. The "real estate" is a non-issue, as there is PLENTY of room on the board. This device was already developed, and testing was being done on a few production prototypes, when the need for a brief delay was noticed.

In this application, there is absolutely no question that the 555 would be the MUCH better choice.

It reminds me of a discussion at the Electronics firm I am consulting for. They needed to add a 1/2 second delay to the startup of a device in a new product. I suggested they add a 555 timer circuit. They looked at me like I had two heads. Their solution was to throw a microcontroller into the product. Come on, guys! It can be done with a 555, a cap, and two resistors. It's crash-proof, too. Whatever happened to K.I.S.S?

K.I.S.S. operates on many levels. Maybe they already use the microcontroller elsewhere,

Reiterating - this is a mostly analog product. It does not already have or need an MCU.

They were thinking of throwing one in, *ONLY* to add a.5 sec power-on delay. There are other chips dedicated to this same function, but the 555 is universal. (Or, at least, it USED to be.) 3 parts; the IC, a cap and a resistor. No need to flash and test. Piece of cake for most assembly houses.

The MCU would require at least a crystal or some other clock. There is also the potential for some RFI being generated, or the MCU

Reiterating - this is a mostly analog product. It does not already have or need an MCU.

That's not reiterating, as that wasn't in your original message. It's adding additional details after the fact. Details that are utterly irrelevant to the design principles I enumerated in my message. This, along with the balance of your reply, shows you can't tell the difference between design principles and blind dogma

It *is* a reiteration, because in my original post, I said, "Their solution was to throw a microcontroller into the product."

This implies the following:

1) This product does NOT already have one.2) It was being inserted for no other purpose than a.5 sec delay.

I think you missed that.

It is pure assumption on your part, to say that I am spouting some kind of "dogma". What "dogma", pray-tell? That using a common, inexpensive, very reliable, simple device is better than a highly sophisticated (comparatively spe

For a startup delay I would have been looking at you like that as well. A 555 is fantastic for cyclical events, but for a one shot delay why not use a simple transistor and RC circuit? The use of a 555 which contains 28 transistors is overkill. What ever happened to K.I.S.S?:-)

Just taking a dig at you, I do not know the full details and sure a 555 may have been the best implementation. But seriously the K.I.S.S principle died when electrical engineers started being taught computer systems engineering ra

The place I worked for was very much analog. My former boss worked for CBS Labs, and was absolutely amazing. He could design almost anything using op amps! I assisted with the design of a number of nice little products.

That company I worked for was bought by another that specialized exclusively in CPU-based devices. Gobbling-up a product line that is 99% analog has proven to be quite the paradigm shift for them, so I have been consulting and providing tech support to their staff for a while, now. I like the

On that topic you may appreciate this: http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_DB9-USB-RS232.pdf [ftdichip.com]
One of my students sent this through a few weeks ago. Very interesting and above all quick solution to the lack of serial problem on new laptops. I work at an industrial plant built in the 60s. Keeping old laptops going, and cheap RS232->USB converters working is becoming a full time job. For an interface that is still very widely used it was made obsolete all too quickly.

You don't even need the 555 if the delay signal consumer can stand a slow voltage ramp w/o oscillating. A simple RC circuit w/ a time constant of 500mS would work. The 555 adds a nice Schmitt trigger, of course.

Ironically, the RESET pin of most PICs have a Schmitt trigger on their input for just this case. If the input if a set/reset flip-flop or some other latching input, the quality of the signal doesn't matter that much. If it's a CMOS input or mosfet gate, then yeah, the 555 makes sense (or a discrete Schmitt or FF).

This is a cool proof of concept and neat little hack. But sound really isn't the best way to do high speed photography.Look at the balloon in the video, you see the end of the action. I think ideally we want to see the moment the pin pricks it. Same with the glass, we want to see the hammer smashing it, not the moment after when the pieces are falling.The CHDK [wikia.com] has been around for awhile and can produce flash sync at least up to 1/60,000th of second [wikia.com] on some pretty cheap cameras.

For a long time, the famous Edgerton photos [google.com] were a staple of physics textbooks. E.g., you could see the (huge) deformation of a tennis ball being hit by a racket. But the Edgerton images are all copyrighted, and it would be really helpful to have CC-BY-SA-compatible photos that could be used instead in places like Wikipedia. I'm the author of some copylefted physics textbooks, and I really haven't been able to find much that's useful. There's this [wikimedia.org] category on wikimedia commons, but there's currently not much in it that's useful educationally. IMO there are a couple of things that would be useful in physics education: (1) an image like the tennis racket, showing how an object's center of mass accelerates even while it's in contact with another object; (2) an image like the bullet going through the apple, which I believe shows that the speed of sound in the apple is less than the speed of the bullet.

In 1973 I had a tobacco tin, a bent piece of foil and a strobe light, airgun and camera.
shutter open, fire airgun, shockwave completes circuit, strobe backlights pellet.
trial and error found the right spot.
The next one I did was a flicker photometer, but it was cool being allowed to bring an airgun into school.
Jerry